6.01 - Diagnostic tool to detect diseases controlled by vaccination

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The diagnosis of most diseases listed is likely to require advice and assistance from your veterinarian.

Disease

Diagnostic tool

Clostridial diseases

Clostridia are anaerobic, spore-forming bacteria widely distributed in nature, particularly in soil. They form resistant spores under stress. These spores and the powerful toxins produced are central to the medical importance of these bacteria.

Clinical signs of clostridial diseases:

  • Tetanus - convulsions initially stimulated by sound or touch that gradually progress in severity.
  • Black leg - severe lameness, swelling on affected leg, depression, fever, dry and cracked skin, sudden death.
  • Black disease - profound depression, abdominal pain, sudden death.
  • Malignant oedema - contaminated wound often associated with calving, local swelling, fever, severe toxaemia and death.
  • Pulpy kidney - convulsions, sudden death.

Botulism

Clinical signs include:

  • progressive paralysis
  • stiff gait
  • muscular weakness
  • uncoordination
  • saliva drooling from mouth
  • unable to rise and breathing becoming progressively more laboured
  • extended hind legs extended
  • tongues that hang out and do not retract when pulled.

Animals affected early in the outbreak will likely die within 12-24 hours, but later in the outbreak animals can live longer and sometimes survive.

Post-mortem may reveal the omasum to be compacted and dry. Bones or other carrier substances may be found in the stomach.

There are several tests available to show if toxic bacterium are present or to show animals have antibodies but they do not prove that a beast has botulism, or has died from it.

Vibriosis

Clinical signs include: 

  • early embryonic death that shows up as early return to service
  • spread out calving
  • very poor pregnancy rates (often less than 50% pregnancy).  
Vibriosis will affect all age groups if recently introduced, heifers are the most affected in herds where the disease is endemic.

Testing can be done with preputial scrapings, for bacterial culture, taken from the prepuce of a bull under instruction from a veterinarian. A vaginal mucous ELISA test through your veterinarian can detect antigen presence using a vaginal swab, this is a mob test.

Leptospirosis

Clinical signs include: 

  • late-term abortion and stillborn calves
  • weak, stunted or deformed calves
  • decline in quantity and quality of milk
  • occasionally mastitis
  • bloody, port-wine coloured urine
  • rough, dry coat.

Cows can be tested with paired bloods for serological testing on both affected and unaffected cows.

Calves and aborted foetuses can be tested for bacteriological isolation of the organism.

Mucosal disease (bovine pestivirus or BVDV - bovine viral diarrhoea virus)

Clinical signs can vary from mild diarrhoea to chronic ill-thrift and wastage in cattle up to 18 months to sudden death of cattle and the signs exhibited will depend on the strain of virus and time of infection. 

If foetuses of naive pregnant females are infected in-utero, immune incompetent calves can become persistently infected (PI) and will usually succumb to infection between six months and two years of age.  

PI cattle spread the viral infection within and between herds.

The diagnosis of mucosal disease will require veterinary input to assist in diagnosis with autopsy, serological testing and histopathology.

Pinkeye

Clinical signs include: 

  • increased tear production and weeping eye/s
  • cloudy cornea (surface of the eye) becomeing pink or yellow if more severe
Some eyes recover but others are left with a permanent scar and the animal will have no vision from affected eyes. Infected animals lose weight and may be completely blind if both eyes are affected.

Bacteriological testing can confirm the cause of pinkeye. Moraxella bovis the most common cause.